# Multi-layer fingerboard?

Discussion in 'Luthier's Corner' started by bound, Jan 7, 2004.

1. ### bound

Dec 28, 2003
Jersey, Baby!
Okay, so i was reading a thread about laminating necks, and the idea that the fingerboard has a lot of effect on the stiffness of a neck came up. So i got to thinking that if i threw a .022 layer of carbon fiber underthe finger board, then a 1/8th inch layer of wood, then another layer of carbon, then the rest of the wood for the fingerboard, at least thick enough to seat the frets. Going by the principle that the layers of carbon wouldn't add much stiffness themselves, but by separating the layers of fingerboard, they'd add stiffness. Or am i just way off?

2. ### pilotjonesSupporting Member

Nov 8, 2001
US-NY-NYC
Any layer of stiffer material added as part of a beam increases the stiffness, in proportion to the layer's distance from the "neutral axis," which is the plane down to middle of the beam which, when the beam bends, is neither compressed or stretched. So, the farther the layer is from the center of the neck, the stiffer the neck is.

So, for stiffness, the best place for the carbon layer is under the fingerboard. (Actually, the very best place would be on the surface of the fingerboard, if it is fretless and therefore not cut by frets.) Putting .044 under the fingerboard will be stiffer than putting .022 under the board and .022 further in by 1/8.

The max stiffness (by far) will be obtained by putting one layer under the fingerboard, and another layer towards the back of the neck. This causes the neutral axis to fall between them. This is the idea behind moving the bulk of the mass to the outsides of the profile in an I-beam.

3. ### bound

Dec 28, 2003
Jersey, Baby!
Cool, I knew the whole deal about I-beams, but wasn't real sure about the differences if any between I and solid beams. thanks for the input!